The division of the powerful Roman Empire in 395 AD into an Eastern Empire with its capital in Constantinople, and a Western Empire with its capital in Rome, was a fact with an extreme importance in European history.

The Eastern Roman empire, better known in historical literature as Byzantium, turned out to possess a far greater vitality and stability than its Western counterpart. While in 476 AD the Western Roman Empire collapsed under the vicious attacks of the Barbarian tribes, Byzantium was to continue its existence for another thousand years. Its excellent military and administrative apparatus, as well as its brilliant diplomatic flexibility, succeeded at preserving its territorial integrity and independence from the neighboring states and the constantly invading Barbarian tribes. Byzantium controlled vast territories in Europe, Asia, and Africa. Its Balkan territories were divided into two regions, named Illyria and Thrace, and each one of those contained a number of provinces. During the 6th century AD the Balkans were raided by Hunns, Goths, and other Barbarian tribes, who destroyed everything and everyone in their way, including towns and villages. A large portion of the local population was killed by the invaders, while other natives took refuge to the mountanous regions and other inaccessible places.

The settlement of Slavic tribes in Central Europe and in the Balkans is one of the most significant results of the Great Migration of Peoples. The Slavs belong to the Indo-European language family, and their formation as a distinctive group within the Indo-European community took place in 1000 BC. They inhabited the vast open spaces of Eastern Europe, north of the Carpathian mountains. The Medieval authors were unanimous that the Slavs were the most numerous of all peoples who inhabited Europe at that time. The Slavs lived in close proximity to the Germanic tribes and thus became known to the ancient Roman writers, who called them "venedi." The Roman history writer Tacitus (1st century AD) thought that the Slavs were related to the Germans, because their way of life was similar in many ways.

During the 4th century AD the three major Slavic groups were already formed: eastern (anti), western (venedi), and southern (slavini). In the middle of the 5th century AD the southern Slavs crossed the Carpathian mountains and settled in the former Roman provinces Panonia (today's Hungary) and Dacia (today's Romania). It wasn't until the beginning of the 6th century AD that the Slavs started crossing the Danube and attacking the Byzantine towns, after which they returned to the northern coast of the Danube along with all the goods and cattle they attained. The increased contacts between Byzantium and the Slavs brought them into the orbit of the Empire's politics. The Slavs were tempted by the rich provinces of the Empire, and by the end of the 6th century they started migrating south of the Danube and settling in the Balkans. The mass migration of Slavs led to their settling not only in the northern and central parts of the Balkan peninsula (Moesia, Thrace, Macedonia, the Rhodope Mountains and so on), but also in territories as far as Corinth in Greece. The remnants of the native Balkan population were quickly assimilated completely. The Slavic tribes started uniting in tribal unions, thus turning into an important political and ethnic factor in the history of the Balkans.

The Slavs were engaged primarily in agricultural activities, as well as in cattle-breeding, hunting, and fishing. From the native population they acquired the skills to cultivate vines and fruits. The Slav artisans were skilled smiths and woodcutters, and had a highly developed production of ceramics. Their pantheon was a typical representative of paganistic beliefs, mixed with politeism. The supreme deity's name was Perun, who was thought to have control over thunders and lightning, and who was believed to be the master of all things and creatures. Other deities were: Volos - the god of cattle, wealth, and family; Svarog - the god of artisans and fire; Dazhbog - the god of fertility; and Lada - the goddess of beaty and love. The Slavs also worshipped the powers of nature and the celestial bodies. The Slavic religious altars were always near old trees, and it was there that they sacrificed lambs, cows, and other domesticated animals. The Slavs also built wooden and stone idols of their deities. The belief in life after death was also present in the Slavs' pantheon, and it governed the burial rituals. The usual burial required that the dead person's body be burned, and then placed in a ceramic pot along with food and some basic necessities.

During the Great Migration of Peoples the proto-Bulgarians asserted their importance as a factor in the history of Central and Eastern Europe. According to the most distinguished Bulgarian medievalist Vasil Zlatarski, the proto-Bulgarians contributed to "the organizational structure and the name of the state and the ethnos" while the Slavs provided "the human resources and the basis for power."

The proto-Bulgarians belonged to the Turco-Altaic language group. Their native land is thought to have been Western Siberia, along the valley of the Irtish River. During the 1st-2nd centuries AD they migrated in the direction of Eastern Europe and settled in the region north of the Caucusus. There the proto-Bulgarians established contact with the local native tribes of Iranian origin, whose cultural achievements and social hierarchy had a substantial impact on their further development. The proto-Bulgarians were mentioned and called by their own ethnic name (Bulgars - there are numerous speculations as to its meaning) for the first time by a Roman chronographer in 354 AD.

In the end of the 6th century AD the proto-Bulgarians were conquered and included in the composition of the powerful Western Turcic Khaganate, whose vast territory extended from China in the east to the Volga River in the West. However, the proto-Bulgarians refused to be subjugated by a foreign rule, and in 632 AD established a powerful military-nomad confederation, called "the Ancient Great Bulgaria" by the Byzantine authors. The confederation's creator, khan Kubrat of the Dulo family, had spent many years in Byzantium, and was rumored to have been sympathetic to the Christian faith. He established friendly relations and a military union with the Byzantine empire, and was granted the title of a patrician - the greatest title and honor ever awarded to foreign rulers by Byzantium. Khan Kubrat established the citadel of Phanagoria on the Taman peninsula as his capital.

After Kubrat's death around 665 AD, the power was transferred to his oldest son Batbayan. However, the internal conflicts between the various tribes weakened the confederation. The neighboring Hazar khaganate seized the window of opportunity and conquered Batbayan's lands. Khan Kubrat's second son, Kotrag, together with a part of the proto-Bulgarians withdrew to the rivers of Volga and Kama, where they and the local tribes created a state called Volgo-Kama Bulgaria, converted to Islam during the 10th century AD. The third son, Asparuh, together with the last remnants of the proto-Bulgarians withdrew to the west and settled in the area known as the "Ongul" in the delta of the Danube river, in what is today Bessarabia.

There is little information left in writing about the way of life of the proto-Bulgarians, and that is why the main body of information and evidence we have today was gathered through archeological excavations. The settlements of the proto-Bulgarians were built primarily in the steppes near the banks of rivers. Most of them lacked walls or any other defense structures, while some were impressive citadels, fortresses, and castles. The majority of the proto-Bulgarians lived in yurtas - large tents made of skins and leather, similar to the Native American wigwams. The primary activity of the proto-Bulgarians was the raising and breeding of all sorts of cattle and especially horses; the horses were used in the powerful Bulgar cavalry, the backbone of the proto-Bulgarian army. The horses were the chief means of transportation, and their meat and the mares' milk were important parts of the proto-Bulgarian everyday diet. Agriculture was slowly finding a place in the activities of the proto-Bulgarians and was primarily a supplement to the cattle-raising, as were hunting and fishing. Most agricultural products were either taken by force from or by exchange with the neighboring Slavic tribes. There were skilled proto-Bulgarian artisans, smiths, builders, and jewelers.

The social structure of the proto-Bulgarians was highly developed and complex. The main social unit was the tribe, and the variety of tribal names - unogonduri, kotragi, chdar-bulgar hints that there were many of them. The aristocracy (khans, boils, and bagains) held all the power and most material posessions, as opposed to the majority of common people. Slavery was widespread, even though it never became the backbone of proto-Bulgarian economy. The slaves were usually prisoners of war, who were used as shepherds, domestic servants, and builders of fortresses and other defensive structures.

The proto-Bulgarian religion was monotheistic and was characterized by the amalgamation of numerous beliefs and cults. The supreme deity's name was Tangra (which in translation means "sky"), the creator of the universe and master of all things and creatures. Tangra was worshipped in shrines, where he was offered sacrifices, accompanied by fortune-telling and other rituals. The supreme priest of Tangra was the khan. The dead were burried with their bodies always oriented north-south, along with food and some of their favorite posessions; sometimes their weapons and their horse would be burried with them. The proto-Bulgarians used a calendar system based on a 12-year lunar zodiacal cycle

SPASSOVDEN (always on Thursday, 40 Days after Easter - “Ascension Day” or “Ascension of the Lord”): The great feast called the Spassovden or Ascension Day is connected to the eternal human wish for health and joy. The feast is a non-fixed one, and it is celebrated 40 days after Easter, always on Thursday.